Brake operating mechanism



Aug. 21, 1934. H. WILLIAMS ET AL BRAKE OPERATING MECiIANISM Filed D66.4. 1930 2 Sheets-Sheet I N V EN TORS /-//7/? Y VV/LL 04/16 061 0/? n/ C5000 Y ix m A TTORNEY Aug. 21, 1934. H. WILLIAMS ET AL I BRAKE OPERATINGMECHANISM Filed Dec. 4. 1930 2 Sheets-Sheet INVENTORS A a/fey 4119M;C5000 ML 0 60/? \\\A\\! ATTORNEY Patented Aug. 21, I934 ApplieationDecembcr 4, 1

" lrout ngropes is)" The invention is particularly adapted for use on! 5the dirigible wheels ofvehicles toprovideaconvenient connection betweenthe brakes and a con troller; such, for in'stance,"as apedal or'handleve t 1 I Obviously the connection 'betweena pedal and a dirigiblewheel must be flexible to allow for:

steering movements 'of the wheel.- Tothisfendgit has beenapractice'heretefore to use acableor afiexible' tension member to connectthe-brake and the pedaL'and in order to prevent variation" in theeffective length-of the cable as the-wheel is steered the-cable ispassed-through a flexible casing secured at one end to the brakehousingand at the other to a-fixed support; -'Ili 'e cas ingis 'ofsuchc'orist'ruction that -it wil1 nes: as the wheel is turned" about thesteering-knuckle, but the distancefrom end to end of the casing alongthe axis of the bore will remain substantially constant. -lilythis-arrangement, the wheel maybe steered without introducing slack inthe operating cable or subjecting the cable to tension by reason ofsteering movements of-the wheel;

Onpulling a cable through a casin'g of the type described above, ifthefaxisof the casing coincid'es withthe line of pull, there will be nothrust on the casing except that due to frictional en gagement thereofwith the cable, IL; on the other hand, the casing is bent, a pull ontheicaQ blewill impart a thrust to the casing tending to straighten itout and the force developed at each end of the casing will besubstantially equal to that applied to the cable. v It'is an object ofthe present invention to utilize the thrust of the casing as wellas' thepull" of the cable to operate the brake. f

An advantage. of this arrangement is that the forces developed arebetter balanced and lateral or transverse thrusts" on the brake partsare avoided.

Other objects and advantages of the invention 5 will appear in thefollowing description of a preferred embodiment and also of amodification thereof and thereafter the novelty and scope of theinvention will be pointed out in the claim.

In the accompanying drawings; Figure l is a view in side elevation of abrake provided with the improved operating mechanism; Fig. 2 is afragmental plan view of the same showing the connection to a brakepedal; r Fig. 3 is a view in section on an enlarged scale taken on theline 33 of Fig. 2; and

an arms?- erican Gab ie Fig. 4 is a fragmental plan view of am'odifiedferm dt brakehperatingmechanism-J V s i In the drawings theinvention is'shown's as ap plied to: a braire pil the type comprising 'a .pair. orshoeswhichi may? be expanded against the" inner periphery (it a brakedrum to arrest:

rotation-"cf the drum. a v

The brake ctrumis-indicate'd by the referencenumeral-;. The brake shoesi11'. arehinged upon a pivot pin la-2? carriedfiby: anhousing. 13 of .thebrake; The shoes :aretpreferably of. 'T-shap'e in crosssection the headof the: Tvbe'aring the usual lining material t4 and the web ofthefr'serving to reinforce the. shoes: lit will bev understoody. ofcoursathatinhthecaseoi a :dirigible wheel the: liousingezm'. is mounted"to with thewheel about: the steering. knuckle; 2 On the side-oppositethezpivotpin 122,; a plate 15 1s mounted on the hous'ingi'anct carriesapair of pins 16.1;Thesepins serve as anchorages' for aipair ofspringsrl'l which are; connected at their oppositeiends to the brakeshoes 11:.v The. springs: thus normally tend todraw the bralte shoestoward each other and away'from tl ieibrake.drinni 1' i j I.

T0 the tree ofleaclr-brake shoe-is secured a connecting-*member 18formed witlr eye lugs w21 disposed in vertical? 'a-linement :toreceive:a ipi-ntle 22 "upon .whi'clrtwos pairs of toggle links are piv-j otallymounted.- pivotally connected to: one ofthe cdnnection. members are;upper. and lower toggle linkslza anirupper and lower toggle links: 24.simi1azm upper and; lower toggle. links 25- and upper and lower toggle?links" 26 are pivotally eonnected te the other connecting member;- e-Thelinks": 23 25- are pivotally connected. together and theilinks 24arep'rvotaily connected to the links 26. Thus; the system of links takesthe form of quadrilateral figure, as clearly shown inI:.Theuppenlinksarespacedifrom:thelower ones, as shown: in'Figa 3. Avspacer collar 27 isfitted between the upper links 24 and 26 and thelower links 24 and 26 and a pintle 28 passing through this collar servesto connect the links together in pivotal relation. The collar 27 isprovided with a lateral socket 29 in which one end of a cable 30 isanchored. This cable at its opposite end is connected to an arm 31 of apedal 32.

There is also a spacer member 33 fitted between the upper and lowerlinks 23 and 25 and this spacer member is formed with studs 34 whichserve as pivots for said links. The member 33 is transversely bored sothat the cable 30 may pass therethrough and at its outer end is formedwith a socket member 35 providing a conical seat for a conical noseformed on a fitting 37. The fitting is applied to one end of a flexiblecasing 38, the other end of the casing being anchored to a suitablesupport 39. The casing is of a type which will maintain a uniform lengthas measured along the axis thereof from one end to the other no matterin what direction or how the casing isbent. As shown in Fig. 2, thecasing 38 through which the cable 30 passes is bent and henceinoperation when a pull is applied to the pedal 32 pressure is exertedupon the cable 30 tending to strengthen the casing. The compressiveforce applied to the casing is substantially equal to "the-*tensile"force applied to the cable. Consequently, therewill be pull on thelinks 24 and 26, and a thrustlon the links 23 and 25 of substantiallythefsame amount tending to force the shoes apart against the pull of thesprings 17. Due to the toggle link connection, a very powerful thrustwill be imparted to the brake shoes producing a very powerful brak-- ingaction.- 7. i I

If the casing were anchored-atbothends the pedalv 32 would need to moveonly half as-far to cause .a given movement of the brakes provided thecasing were incompressible and the cable none extensible. The reason forthis will be, obvious. When the links 24 and 26 are: drawn through acertain distance, theopposite end:of the cable will be moved through alike distance, but, if at thesame. time the casing ispermitted to moveupward, as shown in Fig. 2, against the links 23 and- 25. double thelength of cable will be drawn out of the anchored end of the casing andthe pedal 32 will have to move twice as far as in the. previous .case.Theoretically. then there would .be no power gain' in utilizing thethrust of the casing as well as the pull ofthe cable, but in actualpractice there are material advantages. If the thrust of the casing'werenot used the pullon the links 24 and 26 would result in a lateral thrustof the brake shoes against the housing 13 .which would developconsiderable friction. When the thrust of the casing is applied to thelinks 23 and 25 a balanced condition is obtained which eliminateslateral friction, thus materially reducing the tension requisite in. thecable; Furthermore... since for a given brake movement the cable.movement; isgreater when the thrust. of the casingis utilized the cableis subjected to still less tensile strain. Consequent1y,.there.is lessstretch of the cable and less compression of the casing and because of,the reduced tension inthe cable less frictionis developed between thecable and the casing, As a result the power appliedat the pedal is muchmore efficiently used when the thrust of the, casing as well as the pullof the cable is. employed, be,- cause less energy is .wasted in-frictionand deformation of the casing and cable.

It will be observed that by our arrangement operation of the shoes iseffected throu'gha floating system of toggle links so that the pressureof the freedom in a slotted bearing 43 carried by the housing 13 wherebythe fulcrum is permitted to move parallel to' the plane of the brakeshoes. The levers are formed-with half round bearing surfaces 44-.and.45 which bear against thrust members; 18asecured respectively to thebrake shoes 11. By drawing the outer ends of the levers together thebrake shoes will be pressed out- ,ward into engagement with the brakedrum.

One end of the cable 30 is connected to the lever',40 and theadjacentend of the casing 38 bears againstthe other lever '41-. Thecasing and cable in this instance project parallel tothe plane of. thewheel and not: at right angles thereto, as in the construction shown inFigs. 1 to 3. The casing is bent, however, so that when a pull isexerted on the cable, athrust will be developed in the casing. By reasonof the floating support of the fulcrum pin 42 the brake shoes can'adjustthemselves so that'the'pressure they exert upon thevbrake drum will.b eequalized.

- It will be observed that a new method of operat ing brakes isdisclosed in the present, invention and; while the particularconstructions described above represent two embodiments of theinvention, obviously, the same principle of operation can be applied ina number of different ways andthe particular embodiments can be changedin form, construction and arrangement of parts without departing fromthe spirit andscope of the invention. I

.. We claim: v

, In a brake mechanism including a pair of brake shoes, a plurality oftoggle links pivotally connected in the form of a quadrilateral figure,

said links being pivotally connected at opposite corners of thequadrilateral figures to the brake shoes respectively, whereby ondrawing the intermediate corners of the figure toward each. other theshoes will be spread into operating engagement with the brake drum, aresiliently flexi ble tubular thrust member connected at one end tothelinks at one of said intermediate corners, a fixed support to whichthe other end of the thrust member is secured, a tension member threadedthrough and slidable in the thrust memher and connectedat one end to thelinks at the other of the intermediate corners, and means for applyingtension to the tension memberv at the other end thereof. g I

HARRY WILLIAMS. GORMAN QBURD.

